Author: Dr. Michael Chase, 16th May 2019


This article describes the method and PRELIMINARY outcome of a relatively low cost “laboratory” (kitchen) experiment on the response of seawater pH to increases in atmospheric CO2.

When additional CO2 is added to the air above seawater the chemistry of the water is expected to change, and there is much focus on the pH measure of acidity. I find that the change in pH when equilibrium is established is readily detectable with a low cost portable pH meter with 0.01 resolution, but the measured size of the effect appears to be significantly smaller than reported in the recent scientific literature. This article deals mostly with the experimental method and results.


A schematic plan of the experimental apparatus is shown in the following figure. A 2-litre “airtight” food storage jar contains seawater and air, and portable (battery powered) instruments to measure seawater pH and atmospheric CO2 level, with alterations to the latter by injection of pulses of additional CO2. The water is mixed continuously by a magnetic stirrer.


The actual experimental system used is shown in the following photo, the pH meter is white, and the CO2 meter is grey, with its air intake visible just above the water surface. Food storage technology provided the 2-litre airtight container, the plastic “table” that holds the CO2 meter just above the water surface, and “Cling Film” to protect the CO2 meter from getting wet, with a hole cut for the air intake. Details of the meters used, and of the magnetic stirrer, are given at the end of the article.


The original plan was to use a small portable electric fan to mix-up the air, but it was found that the batteries ran-out after about an hour, insufficient time to achieve pH equilibrium, which is found to take around 10 hours.


CO2 was generated by adding vinegar to bicarbonate of soda in a beaker (with splash guard), injected via an unused ear syringe, a plastic syringe or eye drop dispenser could be substituted:


In a draft-free room the CO2 generated in the beaker can be thought of as a relatively dense fluid which remains there, and which can be drawn into a suitable device and injected into the 2-litre glass container. The aim is to get around 1000 ppm of CO2 in the 2-litre glass container, which is 1 part in a thousand, i.e. 2 ml of CO2 at atmospheric pressure, which can be easily generated and captured.


Seawater samples of around 450 ml each time were obtained from the shoreline near Weymouth in Dorset, on the South coast of England. The shoreline had some seaweed, which may influence the pH. Each sample was stored in a sealed 500 ml plastic bottle in the “laboratory” overnight to warm it to the laboratory air temperature.


Each run of the experiment lasts around 12 hours, which is roughly the observed time required for pH equilibrium to be achieved, with data recording at 15-minute intervals. The runs start mid-morning and run to around 10 pm, a period in which the room temperature remains fairly constant.

The following figure shows early results for 3 runs, one with no injected CO2 (uppermost data), one with injected CO2 such that around 820 ppm was measured (shown in blue with a constant +0.2 shift in all pH values), and one where the final CO2 level was around 1500 ppm:



If the recent growth rate of around 2.4 ppm per year of atmospheric CO2 is maintained then the level at the end of the 21st century will be around 600 ppm, with a change in seawater pH of around 0.15, which is considerably lower than figures quoted in the scientific literature. Note that the change of 0.15 in pH applies to seawater of 8.8 pH, which is at the high end of the observed range. Hydrogen ion concentration at a pH of 7.8 is ten times higher than for a pH of 8.8, so the change of pH in 7.8 pH seawater may be even lower than 0.15.


· pH meter: Hanna Instruments HI 98108

· CO2 meter: Kane-alert-CO2

· Magnetic Stirrer: Hanna Instruments HI 190M

Note: Water in a sealed container gives 100% humidity, and condensation may eventually damage the electrics of the meters, everything is thoroughly dried at the end of each run.


Readers can follow developments, and make comments, at the following website:

An Ocean Acidification Experiment

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Ken Irwin
May 17, 2019 2:09 am

Where are the calcium carbonate minerals (a’la crushed sea shells) lying on the bottom of the “ocean”.

I would consider that a usefull “to do” addition to this experiment – repeat and compare results.

Charles Higley
Reply to  Ken Irwin
May 17, 2019 4:49 am

And, what about the photosynthesizing organisms. Photosynthesis is an alkalizing activity and can raise the pH of a bay or estuary above 10 on a sunny day.

The slight change in pH measured above shows that the seawater was a buffer system. But, without organisms doing their thing in the water, all bets are off.

How many people know that, when water moves through a coral reef, it comes out with a lower pH than when it went in, as general metabolism is a acidifying activity.

There is really no such thing as a constant pH in the real world, just as there is no such thing as a global temperature.

Reply to  Charles Higley
May 17, 2019 5:34 am

Plus 100, Charles and Ken!

Robert W Turner
Reply to  Charles Higley
May 17, 2019 7:08 am

Yes, I like it when my first thoughts appear right at the top of the comments.

Reply to  Ken Irwin
May 17, 2019 6:39 am

are people really this stupid?…..of course they are

You can’t lower pH until you deplete the buffer

George E. Smith
Reply to  Ken Irwin
May 17, 2019 11:22 am

While I applaud the authors diligence in pursuing this experiment; I would prefer an experiment that more closely resembles the reality of the ocean environment.

So the first thing to eliminate is the magnetic stirrer. There’s no such thin in the oceans, and the effects of stirring totally distort what is actually going on. The author mentions ten hours for the system to reach pH stability. That is a surprising amount of time, but very important.

A recent article in the San Jose Mercury news paper, purported to describe a very scientific study by supposed scientists and chemists working at the Monterey Bay research facility.

The word pH was never mentioned in the article; just “ocean acidification”. So much for the “Scientific” claims. How could any chemist talk about “ocean acidification” and never mention pH, so I dismissed the entire article out of hand. The deep ocean which is in reasonable Henry’s law equilibrium with the well mixed atmosphere, is NEVER” acidic, and on line papers I quickly found described the pH as being in the 7.8 and higher range, up to 9.0.

The particular gist of this SJN article was the assertion that Silicon Valley CO2 emissions from automobiles was “pouring” through a coast range pass into Monterey Bay and acidifying it.

Well if they had measured their acidification in San Francisco Bay, which is much closer and shallower than Monterey Bay, they could have found even more massive ocean acidification; enough to eat holes in the bottom of ships in SF Bay.

I can think of few locations better for dumping automobile exhaust CO2, than Monterey Bay. It is very deep very close to shore. 10,000 ft depths are the order of the Monterey Canyon.

I did find two graphs showing the pH of the North Atlantic, and the North Pacific from the surface, going down to 3,000 meters.
At the surface, both oceans are very alkaline in the pH 8-9 region, and that pH drops rapidly down to 500 meters. Unfortunately there was no ocean Temperature profile to go along with that.

The north Pacific dropped down to the 7.8 or so range in 500 meters, and then slowly inched back up over the next 2500 meters, to respectably alkaline numbers.

So what is going on. Well for starters, you need to know that the downward long wave IR radiation from the atmosphere that is “warming” the planet, is all absorbed in the top 50 microns of ocean surface water which is thus warmed above the temperature of the top meter of ocean water. As a result of this temperature spike at the surface, the very surface layer has a lower equilibrium CO2 absorption.
Below that surface “film”, the temperature drops more or less linearly down to the thermocline, so the amount of CO2 the water can hold increases with depth, so the dissolved CO2 diffuses under a concentration gradient diffusion process, and literally pumps CO2 from the surface down to the colder ocean depths. Because of the constant depletion of that very thin surface layer, the water is soaking up CO2 and pumping it to deeper water.

So that 10 hours or so that our present author mentions for pH stability, is very important.

What is absorbed into the ocean surface is GASEOUS CO2, which doesn’t acidify anything. You just have to open a bottle of 7-up to see that what is dissolved in the pop is CO2 gas, which immediately bubbles out when you relieve the pressure.

So what happens now to that dissolved CO2 gas over apparently some hours, is that the CO2 reacts with the hydroxyl ions from the dissociated water, to form the weak acid: izzat (COOH)2. IANACH I think that is carbonic acid. The point being that is how dissolved CO2 eventually does change the ocean water pH, but because of the temperature gradient of the deep oceans, the “acidification” reduces at greater depth; not increases.

Anybody done any scuba diver on oceanic reefs at 500 meters depth to see how acidification is damaging the reef environment ??

No if you want a benign place to put some local excess CO2, Monterey Bay Canyon is a great place to put it.


May 17, 2019 2:10 am
Dodgy Geezer
May 17, 2019 2:18 am

This experiment is no good!

Don’t you know that only modelling predictions are acceptable nowadays?

Reply to  Dodgy Geezer
May 17, 2019 12:16 pm

Exactly! Haven’t we learned by now that playing with numbers on a computer is vastly superior to going out in the field and doing actual science?

Reply to  Dodgy Geezer
May 17, 2019 12:50 pm

Did they have Institutional Ethics Approval – can’t publish without that.

May 17, 2019 2:25 am

what’s the end result, how do fish react

Reply to  b carey
May 17, 2019 7:47 am

I think you meant to ask “How do the fish feel?” Also, how do the polar bears feel about the fish?

Dodgy Geezer
May 17, 2019 2:29 am

Oh, and I’m afraid that Nature will not be able to print details of your interesting experiment.

Our peer review team found a number of fundamental flaws with your equipment, but they felt that there was no point in detailing them, since you might then point out that they were simply being put forward as excuses to drop your paper. The paper does not meet our strict standards, as it is obviously written to point out flaws in the current Climate Change hypothesis, which is settled science. And anyway, we have just discovered that there is no room to publish it in the next, or any future issues….

Michael S. Kelly LS BSA, Ret
Reply to  Dodgy Geezer
May 17, 2019 5:07 am

In other words, it is “flawed” and ‘thoroughly debunked.”

Reply to  Dodgy Geezer
May 17, 2019 5:37 am

You are keeping me laughing!
b. cary’s was good, too.
You are on a roll, this morning Dodgy!

May 17, 2019 2:37 am

CO2 content on water is determined by Henry’s law and therefore the water temperature. What was the temperature of water?

Old England
Reply to  MAK
May 17, 2019 3:42 am

That was my first thought.

Tom in Florida
Reply to  MAK
May 17, 2019 4:21 am

” Each sample was stored in a sealed 500 ml plastic bottle in the “laboratory” overnight to warm it to the laboratory air temperature.”

So not the natural sea temperature, but laboratory air temperature. Caveat emptor.

Reply to  MAK
May 17, 2019 4:51 am

Right. My first thought as well. This simple experiment should be run at different temperatures from ~0.5 C to around 40 C.

Clyde Spencer
Reply to  MAK
May 17, 2019 7:46 am

Actually, temperature, CO2 partial pressure (actually, fugacity), and salinity effect CO2 solubility in sea water.

Loren Wilson
Reply to  Clyde Spencer
May 17, 2019 10:09 am

Now we’re talking some real phase equilibrium thermodynamics when we get to use the term “fugacity”. The fugacity of CO2 in air at ambient temperature and pressure is very close to its partial pressure since the mixture is very close to ideal. The fugacity of CO2 in the liquid phase is extremely hard to model, especially for a biologically active sample. I do like the experimental approach of the measurements outlined above. The ratio of water to air will affect the resulting equilibrium, but the ratio in the experiment is probably more conservative than reality. This is not just a function of the depth of the water column, but depends on mass transport. Most of the water in the ocean is not at equilibrium with the CO2 in the air above it.

Lewis P Buckingham
May 17, 2019 2:38 am

In the ocean one would have to correct for surface warming, which would outgas the CO2,thus raising Ph while turnover of the water would revert the Ph to the existing level.
Also the experiment does not allow for buffering from rocks in seawater which would presumably resist Ph change.
Given these caveats the results point to an even less of a Ph change to neutral than found in this excellent empiricle experiment.
Speaking recently on this site
Dr Peter Ridd commented that it was unclear what Ph change due to extra dissolved CO2 would do to coral reefs.
One wonders whether the intrinsic metabolism of the coral symbiots would simply use the extra CO2 to build themselves, thus naturally stabilising the Ph for the corals themselves.The extra CO2 would also drive the reaction to build CaCo3.H2O…, building coral skeletons.
Hopefully if he or those who follow him are allowed, such experiments could be planned, run and replicated.

Reply to  Lewis P Buckingham
May 17, 2019 5:00 am

The buffering capacity of the oceans is obviously quite high. That’s where all the world’s limestone came from, which holds most of the CO2 in our earlier atmosphere .. a process that operates over geologic timescales, not the mere 10 minutes to reach equilibrium in this tabletop experiment.

There is no such thing as “ocean acidification”. There is “limestone making”.

Crispin in Waterloo
Reply to  Lewis P Buckingham
May 17, 2019 9:53 am

We also saw here an article recently that examined the mechanism by which simbionts are driven out of host coral. The bottom line was: a lack of CO2.

Higher temperatures in the water around the coral drives up the absorption rate of CO2, which is taken out of the water, leaving the pH higher than before.

This is a basic mechanism of coral growth. Anything that absorbs CO2 has the by-product of raising the pH in the water. This explains why the pH in a large enough reef is higher than the surrounding ocean water – it is short of CO2.

As with all terrestrial plants that have enough water, the limiting factor on growth of plants in the ocean is the availability of CO2 (food).

Reply to  Crispin in Waterloo
May 17, 2019 5:39 pm

Not just CO2, but the trace Iron necessary to facilitate production of chlorophyll (Chlorosis) and photosynthesis..

I have a pet theory (hypothesis?) that suggests that maybe some of the bleaching is due to a lack of dissolved iron in the tropical waters making the algal symbiots too weak to reproduce.. and thus the coral dies.

Would love to see some experimentation on the idea.

Reply to  Ron
May 19, 2019 11:19 am

Though chlorophyll, itself, has magnesium in the heme ring, not iron. And, if I am not mistaken, intracellular calcium would poison it, as does oxygen when the carbon dioxide concentration gets too low.

High Treason
May 17, 2019 2:41 am

It is even easier to show that the ocean acidification thing is a load of garbage via basic facts:-
There is 48 times more CO2 in the oceans than in the atmosphere.
Doubling the concentration of CO2 in the oceans lowers pH by .4 points
The oceans are around pH of 8- alkaline.
For this argument, I am not even going to use the the huge effect of buffering from rocks on the ocean floor, which are what make the oceans alkaline.
If all the extra CO2 added to the atmosphere by evil humans recycling fossil fuels/plant food dissolves in the oceans, the atmospheric concentration needs to increase 48 fold to double the CO2 concentration in the oceans. To lower pH by .4 to pH 7.6 (still basic) requires the equivalent atmospheric concentration of 408 x 48=19,584ppm !!IE .04% to 2%.
It will need to double again and still not hit acidity. Still no factoring the buffering capacity of rocks.
Anyone still believe the fairy tales?

Mike Haseler (Scottish Sceptic)
May 17, 2019 2:43 am

Sea water contains a lot of living creatures, so I would be concerned with photosynthesis & possible decay.

I think it would be sensible to use a coarse filter on the sea water to avoid anything big getting in (but you may want an active population of smaller creatures).

If possible, would be to maintain the original temperature and exposure to sunlight – that avoids any effects purely related to changes in temperature on the creatures (like mass die off)

I would also do a “control” – by boiling the sea water and then letting it cool – if that were giving much the same results then the effect of living things is probably small (over a short time).

William Baikie
May 17, 2019 2:57 am

Earth’s oceans hold over 50x the CO2 of our atmosphere. A warming earth also means a warmer ocean. Warmer water can hold less CO2. Ergo: less carbonic acid and higher PH. The slight increase in atmospheric CO2 would balance this effect but I’m not convinced we should get ocean acidfication.

Bruce of Newcastle
May 17, 2019 3:21 am

Nice experimental work! I’ve done plenty of tests like that in labs over the years. About the only thing different I’d’ve done is use a CO2 cylinder, regulator and a rotameter. But that would just be to make CO2 supply easier.

As to your data, seawater pH changes considerably more than that due to temperature. Willis Eschenbach had a nice graphic of the pH versus latitude and depth. Ranges from 7.2 to 8.1, which is nearly a 10 times change in [H3O+].

The other aspect is the activity of HCO3- ions. Calcification is dependent upon pH and upon availability of bicarbonate. So as you increase pCO2 you are reducing pH but also increasing [HCO3-] availability. And as corals annually have massive numbers of offspring the effects of natural selection would rapidly kick in to favour the progeny most able to cope with lower pH/higher [HCO3-].

Unfortunately that isn’t easy to test in a 3 year PhD project, so we don’t have any decent data on coral adaptability.

Here is Willis’s pH article:

A Neutral View of Oceanic pH (2015)

May 17, 2019 3:40 am

Full marks for effort but, as other posters have pointed out, there are so many other factors to take into account (not to mention the question of scale) that it is not actually very useful.

Robert W Turner
Reply to  Susan
May 17, 2019 7:14 am

If anything, it shows the maximum pH change possible on 25 degree seawater with aCO2.

John F. Hultquist
Reply to  Susan
May 17, 2019 10:39 am

Same thought with me. Sort of a neat first effort.

I wonder if they say how many thousands of dollars this cost.
What amount are they asking for in the next grant?

May 17, 2019 3:42 am

If I take a couple of Tums and then check my urine pH, think I would be able to publish?

Tom in Florida
Reply to  pochas94
May 17, 2019 7:47 am

No, they would probably piss on your results.

J Mac
Reply to  pochas94
May 17, 2019 1:00 pm

Publish, no. But you might be able to sell it the democrats as a salacious dossier, if you can allege Trump collusion.

May 17, 2019 3:43 am

Perhaps you should inform David Attenborough and the BBC, who clearly understand nothing about acid-base equilibria.

Carbon Bigfoot
Reply to  Graemethecat
May 17, 2019 4:14 am

Link Not available

Reply to  Carbon Bigfoot
May 17, 2019 6:22 am
May 17, 2019 4:11 am

Great! Now all the baking soda is going to be restricted by stupid laws.

You’ll have to sign a Statement of Intended Usage and swear on a copy of Michael Mann’s hokey hockey stick book that you will only use it for making biscuits or cookies or to counteract your hyperactive stomach acid levels, which are what are really responsible for ocean acidification. And you’ll have to have the recipes in your hands when you show up at the checkout counter to pay for it.

Stock up on baking soda now, people. We’re doomed!

Steve O
May 17, 2019 4:52 am

Too soon for conclusions maybe, but it deserves more attention. It would be interesting to scale up the experiment, perhaps to bathtub size, and verify the results. I wonder what supports the figures from the scientific literature.

Steven Fraser
Reply to  Steve O
May 17, 2019 6:14 am

And, add fish. In fact, scale up to a fish tank.

Reply to  Steve O
May 17, 2019 6:24 am

Make sure to lime the bathtub water for strict comparability.

May 17, 2019 4:53 am

A study of seawater pH near active volcanic CO2 vents in the Mediterranean (Kerrison et al., 2011) found that the pH immediately adjacent to the vent was still alkaline, despite being subjected to the equivalent of nearly 5,600 ppm CO2.

Partial pressure and fugacity (μatm) are a little lower than what the mixing ratio (ppm) would be, depending on temperature and humidity.  However, they are close.  A partial pressure (pCO2) of 350 μatm generally equates to about 350 ppm in the atmosphere.   At nearly 5,600 ppm CO2 the seawater was still alkaline, not acidic.

Clyde Spencer
Reply to  David Middleton
May 17, 2019 7:56 am

Konrad Krauskopf remarks in his textbook on geochemistry that it is very unusual for sea water to even get to a pH of 7. The few cases observed were unmixed, anoxic zones rich in hydrogen sulfide. I think that I have read that the water immediately emanating from Black Smokers is acidic, but quickly become neutralized by mixing with the surrounding alkaline water. Yet, neither the temperature or acidity are barriers to abundant life around the Black Smokers.

Reply to  David Middleton
May 17, 2019 9:14 am

“At nearly 5,600 ppm CO2 the seawater was still alkaline, not acidic.”
pH 7, the neutral point of pure water, is irrelevant in a buffered solution. As I often point out, if your blood reaches pH7, you will be dead (from acidosis). The question is always what will be the consequences of a shift in buffer equilibrium.

In sea water, the consequence is a conversion of the alkaline species carbonate to bicarbonate. This increases the tendency of calcium carbonate (shells etc) to dissolve – simple equilibrium chemistry. pH 7 has no role here. The main reduction in carbonate concentration takes place at much higher pH levels.

Clyde Spencer
Reply to  Nick Stokes
May 17, 2019 11:57 am

If you are really interested in the “… consequences of a shift in buffer equilibrium,” then you should acknowledge that living calcifiers usually (if not universally) have chitin and mucous covering the surface of the shells and the reaction you are referring to takes place preferentially with the shells of dead organisms, which have lost their protection. Calcifiers are able to repair damage so the primary ‘cost’ is the expenditure of more energy to live in an environment where carbonate can dissolve.

Examination of a typical Bjerrum Plot shows that calcifiers tend to live most happily at a pH that corresponds to a minimum concentration of carbonate and near the plateau of bicarbonate.

Lewis P Buckingham
Reply to  Clyde Spencer
May 17, 2019 2:18 pm

It is interesting that sea creatures learned to adapt to pH changes by the use of metabolic pathways as they evolved, thrived and multiplied.
If they had not, we would not exist.
Our own blood pH of 7.4 mimics that of seawater, as does our reliance on sodium and chloride ions in our makeup.
This points to our origins in an alkaline salty environment

Clyde Spencer
Reply to  Lewis P Buckingham
May 17, 2019 4:02 pm

Lewis P Buckingham
Calcifiers have different ranges of optimal pH. I suspect that the particular range is related to what the pH was when the specie first evolved.

Reply to  Nick Stokes
May 17, 2019 1:04 pm


Your point is valid… but I was just pointing out 1) that the process is essentially instantaneous, 2) it’s a diminishing returns function and 3) it’s pretty well insignificant below about 1,200 ppm… and even then, it’s not a “crisis”.

Reply to  Nick Stokes
May 18, 2019 3:08 pm

Nick….what are the cliffs of Dover made of?…..when did those sediments form?…and what were CO2 levels then?

Reply to  Nick Stokes
May 18, 2019 7:51 pm

“This increases the tendency of calcium carbonate (shells etc) to dissolve…”
Yes, but it also increases the tendency of limestone rock to dissolve as well. The net effect is by adding CO2 to such a system is you actually INCREASE both the bicarbonate AND carbonate in solution. Simple experiment…. add finely powdered CaCO3 (limestone) to a flask of water. Bubble in CO2. Pretty much the only thing that happens it that the pH stays relatively constant until all of the CaCO3 has been dissolved with the net effect of increasing both HCO3- and CO2- concentration.

Phil Rae
Reply to  Nick Stokes
May 19, 2019 12:41 am

Nick Stokes…..As a regular visitor to WUWT, I am well aware of your position regarding CAGW but I consider your comments and input to be fairly reasonable, albeit biased. However, whenever you comment on “ocean acidification” it strikes me that you really don’t understand much about chemistry, particularly as it relates to biological systems & buffers. Furthermore, your repeated allegation that alkaline carbonate is being transformed into less alkaline bicarbonate is ridiculous. The concentration of carbonate ions in seawater is negligible because it is mostly present in the form of solid and relatively insoluble calcium and/or magnesium carbonates. These normally insoluble carbonates are in equilibrium with the bicarbonates and calcium/magnesium/hydrogen ions in solution. Any increase in H+ ions from CO2 dissolution will also generate bicarbonate ions. Any dissolution of solid carbonate will release the corresponding counter-ions (Ca2+/Mg2+) and the ultimate effect on the system as a whole will be controlled by the equilibria between the various ionic species and the solubility products of the respective solid phases (aragonite/calcite/magnesite, etc). It should also be noted that any slight fall in pH is accompanied by a decrease in CO2 solubility in the aqueous phase since there is an equilibrium between the gaseous phase and the bicarbonate/H+ pair in solution, too.

Bicarbonate ions are the principle buffering species of the (CO2/HCO3-/CO3- -) system in the natural world and this amazing buffering system is astonishingly good at maintaining pH in biological systems, including our own bodies, incidentally. All of this is perfectly explained by the Henderson-Hasselbalch equation which explains exactly how buffers work and why your arguments on this particular topic make no sense whatsoever.

In general, a buffer is capable of holding a system stable around the pK value of the buffering species despite a 10-fold increase in any of the species seeking to disequilibrate that system.

Reply to  Phil Rae
May 19, 2019 2:27 am

“The concentration of carbonate ions in seawater is negligible because it is mostly present in the form of solid and relatively insoluble calcium and/or magnesium carbonates.”
That just isn’t true. Here for example is the Bjerrum plot of the equilibria, showing carbonate at about 10% of bicarb at normal sea-water conditions. It is usually quoted as 11%. This equilibrium must be obeyed in addition to the solubility equilibrium for CaCO₃. That is actually my point. We sit at the acid end of the HCO₃⁻/CO₃⁻⁻ buffer system, so each added CO₂ dissolves a molecule of CaCO₃. It’s true that that stabilizes the pH, but that isn’t the effect of interest.

“In general, a buffer is capable of holding a system stable around the pK value of the buffering species”
The system isn’t held stable. It is the pH that is stabilized. The other reagents are consumed while that is happening, and that is what matters here.

I have an active calculator here which solves the equilibrium equations to show how that works. There is more detailed explanation and data here.

Phil Rae
Reply to  Nick Stokes
May 19, 2019 9:46 am

Hi Nick!

Many thanks for taking the trouble to respond….much appreciated! I’m glad we agree that, despite much media hysteria & ridiculous alarmist comments, there is no risk of ocean acidification due to any credible future increases in atmospheric CO2. I understand the chemistry involved so none of this is new to me. However, I find your comments above (and your links) to be disingenuous to say the least.

There is an essentially infinite supply of solid calcium carbonate in contact with seawater and the presence of Ca2+/Mg2+ at significant concentrations (~450ppm & ~1250ppm, respectively) have a significant bearing on the various equilibria due to the low solubility products of the mineral species involved.

So, while there may be some limited dissolution of CaCO3, there will be no real “ocean acidification”. I’m sure you are also aware that marine life manufactures protective shells from soluble bicarbonate rather than the much less available carbonate ion at physiological pH.

Reply to  Nick Stokes
May 19, 2019 11:25 am

Only true for arterial blood, Nick. Venous blood from exercising muscles easily reach 6.9 pH, resulting in cramps, especially when other factors are considered.

Robert of Texas
Reply to  David Middleton
May 17, 2019 3:33 pm

I am no underwater volcanologist, but I am pretty sure that the vent waters coming out of undersea vents has a mixture of chemicals other than CO2. If there is sulfur present, then it would greatly affect any pH measurements (assuming heat and come basic chemistry is lurking about).

So your point that 5,600 ppm CO2 did not create acidic water is made even more poignant – there was likely H(+)SO3(-) and H2(++)SO4(–) in the immediate area.

The natural ability of the oceans to buffer against a wide scale change in pH is huge.

R Shearer
Reply to  Robert of Texas
May 17, 2019 9:08 pm

Yes, the ability of seawater to act as a buffer is from ionic species already present.

Dr Deanster
May 17, 2019 5:09 am

What a great experiment! There’s no agenda that can be assumed, as this little experiment is what it is. A few thought to make it even more revealing.

– noticed your control was 450ppm. That probably due to out gassing due to temp increase. Control your temps, in fact …. see what happens as temp rises, or as temp cools.

– run you a control with nitrogen oxygen mix. … see if pH goes up in an atmosphere with no CO2

– run a series with added buffer, to see what happens if the biological system responds.

There’s all kinds of questions you could ask and somewhat answer.

katie mccready
May 17, 2019 5:29 am

so many of the data bases- like this one below on direst atmospheric measurements of CO2 are no longer available via the schripps institute, as they once were.

this one (above) only goes up to 2008 – however – notice that the values change seasonally and what causes these changes is due to many contributing factors

temperature as already mentioned in previous posts for example- especially the inherent temperature of the ocean – and

no scientist living or dead knows all the factors that contribute to oceanic temperature changes.

photosynthesis amounts and rate – quasi periodic and very large oceanic circulation changes – etc, etc.
climate modellers attempt to put in as many variables as they can – they’ve been at it for decades now

the empirical data is clearly showing they’re not working very well – arguably because they don’t have much of a clue how all the variables interact – the dynamics of climate at this stage in the history of science cannot be adequately modelled

interesting – Dr of what – not to be rude – is my question?

the last time I looked

John M. Ware
May 17, 2019 5:31 am

I enjoyed the article, and the comments. I have a slightly unrelated question: What is the chemical composition of hogwash? Have any scientific tests been run on it? With all the hogwash being emitted by certain politicians and candidates, shouldn’t we know its chemical makeup and how to neutralize any inimical effects? Just a thought . . .

May 17, 2019 5:35 am

my experiment relies on the theory that rising sea levels are partially the result of fishing quotas.

If the number of fish and whales taken from the sea is reduced, their numbers will grow. These animals live in the water and therefore displace their body volume in sea water. This naturally raises the sea level.

Obviously some animals, like whales , sometimes float around a bit, or even jump right out of the water so there is a modelling requirement, but the basic principle is sound.

My experiment involves filling a bath to the brim then inserting a space hopper, or other large fish-like simulation. According to the hypothesis, the water will overflow. If it does, I will write a paper with Michael mann and I will become as famous as he is. (but wetter)

Tom in Florida
Reply to  EternalOptimist
May 17, 2019 7:48 am

I can only say Eureka!

Joe Chang
May 17, 2019 5:50 am

obviously you haven’t learnt the “science” of “data adjustment” and of course, as with CO2 driving Globull Warming, CO2 itself has weak direct affect, so just add amplification factors, perhaps 6X, then show how that puts the World oceans on the “tipping point” that any additional CO2 will cause run away acidification. Data , schemata!

May 17, 2019 6:46 am


Regarding this: “insufficient time to achieve pH equilibrium, which is found to take around 10 hours. I do not see in your graphic anything reaching equilibrium. Where does that claim come from?

Alan Tomalty
May 17, 2019 6:54 am

“A 2-litre “airtight” food storage jar contains seawater and air,”

How do you inject the CO2 if the jar is airtight?

Reply to  Alan Tomalty
May 17, 2019 9:55 am

“How do you inject the CO2 if the jar is airtight?”

A needle through the diaphram..

Neil Jordan
May 17, 2019 6:58 am

One-third marks, but in the correct direction for debunking “acidification”. See 2013 WUWT:
This experiment covers only the bicarbonate buffering system. Commenters added the carbonate (sea floor) buffering system. There is also a third borate buffering system that accounts for another third. See my comment in the 2013 WUWT article:
Neil Jordan September 25, 2013 at 2:00 pm
Re Sabertooth says: September 25, 2013 at 11:43 am
The pH ceiling of 8.3 is explained in Emerson & Hedges Chemical Oceanography, which also explains a pH floor of 7.6, also alkaline:
This reference also includes borate buffering in addition to the carbonate and bicarbonate buffering that are customarily used to describe seawater
According to Frankignoulle (1994):
borate buffering accounts for 30% of the global buffering effect in seawater.

Reply to  Neil Jordan
May 17, 2019 9:26 am

“This experiment covers only the bicarbonate buffering system.”
Really? Why so? Borate was not removed from the sea water, and its buffering remains in effect.

May 17, 2019 7:09 am

The world’s oceans hold 1.35 billion cubic kilometers (320 million cubic miles) of water. The average depth is 12,100 feet.

I was taught by one of the best marine chemist at the time (circa 1960s) that the oceans, besides being far larger than most people comprehend, were a strongly buffered system. We had to keep that in mind anytime we were sampling and interpreting the results. Note ocean acidification was been discussed even then, before CAGW arrived, it drove my professor nuts.

Justin Burch
May 17, 2019 7:12 am

I attended foundation lecture for the public on the horrors of climate change causing ocean acidification in a fund raiser attended by several local politicians. We were shown similar experiment on a larger scale with coral added into the bottles. We were shown before and after images of how the coral died when the pH was lowered. During the question and answer section I asked how much they had changed the pH and over what time period and how did that change compare to the possible ocean acidification? I said that corals can likely tolerate a small slow increments but just about anything will die if you dump enough acid on it all at once. The presenting ‘scientist’ got extremely uncomfortable. He literally started shifting his eyes back and forth and then, by his body language, acted like I had caught him out. He said he wasn’t sure because they had done many experiments and he wasn’t sure which experiment matched the images he had shown, and he would have to get back to me on that. I said surely since this was his experiment he could provide an estimate, 1, 2, 3 units? Over a week, a day, an hour? He shifted to but ocean acidification was a very important topic and needed funding for in depth research if we were to save the reefs and blah blah blah never actually answering me. To my surprise, several others including the politicians, picked up on that and spoke to me at the wine and cheese post presentation. Underlings kept trying to insert themselves between me and the politicians. I got a lot of dirty looks. I never heard if he got the money.

Nick Schroeder
May 17, 2019 7:17 am

The pH scale is log so every whole number is a power/factor of ten.

By definition pH is the negative exponent of the hydrogen ion concentration.

For instance, pH 9 is 10^-9 or 1 part per billion, 0.000000001.

pH 8 is 10^-8 or 10 parts per billion, 0.000000010.

To go from pH 9 to pH 8 is factor of 10 or 1,000%!!!! Makes 26% look trivial.

Ocean “acidification” of pH 8.2 to pH 8.1 is a change in H ions of 1 ppb.

I’m fairly certain the ocean flora and fauna don’t even notice.

May 17, 2019 7:40 am

Good experiment, but I think too generous to the fruit loops who scream disaster. The atmosphere at sea level is about 1000 times less dense than the ocean, but the ocean has about 1000 times more mass, so their volumes are roughly comparable. Your sea water, then, should be about the same volume as the air above it, but you experiment seems to have much less water than that.

William Astley
May 17, 2019 7:40 am

Your results are common sense.

Ocean acidification is, however, only an issue if humans caused the atmospheric CO2 rise. There is observational evidence that atmospheric CO2 is tracking temperature. For that to be true there must be a larger source of CO2 into the biosphere and a larger sink of CO2 out of the biosphere.

New organic sinks of CO2 discovered.

This recent observation that C14 is making to the deepest ocean disproves the CAGW created Bern model of CO2 sinks and sources and resident times.

Bomb C14 Found in Ocean Deepest Trenches

‘Bomb Carbon’ from Cold War Nuclear Tests Found in the Ocean’s Deepest Trenches

Bottom feeders
Organic matter in the amphipods’ guts held carbon-14, but the carbon-14 levels in the amphipods’ bodies were much higher. Over time, a diet rich in carbon-14 likely flooded the amphipods’ tissues with bomb carbon, the scientists concluded.

Ocean circulation alone would take centuries to carry bomb carbon to the deep sea. But thanks to the ocean food chain, bomb carbon arrived at the seafloor far sooner than expected, lead study author Ning Wang, a geochemist at the Chinese Academy of Sciences in Guangzhou, said in a statement.

This is an excellent summary of the CO2 resident times and the creation of the Bern model dogma.

David Murray
Reply to  William Astley
May 17, 2019 11:00 am

Thank you so much. A fascinating link . A brilliant history.

John Collis
May 17, 2019 7:58 am

What would be the pH if the temperature of the “seawater” was 37 degrees Celsius?
I hypothesise (guess) that it may be around 7.4.

Clyde Spencer
May 17, 2019 7:59 am

Dr. Michael Chase
Your pH values are on the high side of what is usually reported. Have you given thought to calibrating your instruments?

May 17, 2019 8:08 am

It is unclear for what purpose this experiment was performed. The dependence of CO2 concentration in water on its partial pressure in air has long been studied, the values of the Henry constant are known:;_ylt=A0geKeoWut5cbYsAODBXNyoA;_ylu=X3oDMTByMjB0aG5zBGNvbG8DYmYxBHBvcwMxBHZ0aWQDBHNlYwNzYw–?p=henry+constant+for+co2+in+water+at+different+temperatures+char
Also known is the dissociation constant of carbonic acid in pure water and in an artificial mixture similar to seawater. Knowing the partial pressure of CO2, the temperature and the dissociation constant, one can calculate the pH.
In other words, this experiment could only show how the results for water samples taken “from the shoreline near Weymouth in Dorset” differ from the calculated values. And in order to explain this discrepancy, it is necessary to know, in as much detail as possible, the chemical composition of water, primarily the concentration of carbonate and bicarbonate ions, as well as borates and silicates, which have a buffer effect.
By the way, the concentration of carbonate ions in sea water exceeds the concentration of dissolved CO2 by more than 20 times, and the concentration of hydrogen carbonate ions is greater than the concentration of CO2 by more than 170 times (Table 1.2 on page 26 in )
From this it follows that the increase in CO2 concentration in the atmosphere from 0.03 to 0.04% over the last century should practically not have changed the acidity of the ocean.

Robert of Texas
Reply to  aleks
May 17, 2019 3:40 pm

While CO2 effects on sea water may have been studied, and you may be able to calculate pH in a “perfect setting”, science is all about measurements. It’s the taking of measurements and then trying to figure out why they do not match theory that leads to important discoveries.

I encourage people to make their own measurements. It might not advance the debate on the effects of atmospheric CO2 on the oceans, but it will advance at least one person’s understanding and might lead to a curious finding.

michael hart
May 17, 2019 8:10 am

Suggestion: Try doing the experiment again and add carbonic anhydrase to the solution. You might see a difference at the beginning, depending on various experimental factors.

The experiment reaction rate is more susceptible to mixing rates and other factors than might first appear to be the case. In fact it is sometimes used as an simple undergraduate demonstration experiment where a saturated (with added excess solid CO2) solution containing indicator is neutralized/basified with added sodium hydroxide solution. The color changes immediately upon addition of base and then, after about 10 seconds or so, reverts back to mildly acidic as le Chatelier slowly drives it back again with the excess CO2.

Why would that matter if it doesn’t change the final result? It speeds up the kinetics of the CO2+H2O/H2CO3 exchange over a million-fold. It is thus ubiquitous in nature for obvious reasons, and present in the biofilm covering the surfaces of all water bodies on earth. The rate of this chemical reaction determines how fast oceans can absorb (or expel) carbon dioxide. In the real-world ocean experiment we never get to see the end point, only the beginning of the experiment because oceans are so vast, mixing is relatively slow, and the final equilibrium end-point is never reached.

Any climate model that ignores this factor is probably useless.

May 17, 2019 8:43 am

Dr. Chase ==> You might want to read the two essays I wrote here some time ago on this topic. A great deal of effort has been put in by a group of OA scientists to change the way OA experimentation was being done and bringing about better and more real, dependable results.

You might review “the European Project on OCean Acidification (EPOCA) – which produced the booklet “Guide to best practices for ocean acidification research and data reporting” .

May 17, 2019 8:54 am

You guys are something else. Get yourselves a bucket cold water and a heat gun and try putting physical heat through the surface of water. The heat is rejected. Only radiated energy penetrates the surface of water. Have a nice day.

May 17, 2019 9:16 am

As a chemist, I am outraged at calling a faint neutralization of a mild base “acidification.” That is emotional, like calling climate skeptics “deniers.” High school and college Chemistry class acids are extremely strong and burn a hole in your skin in less than a second if you splash a drop on yourself.

pH of the ocean is 8.1. Your blood is 7.4–so that is likely the ideal for life. Organisms can thrive in an actual acidic environment of say, pH6.

Reply to  ladylifegrows
May 18, 2019 5:38 am

The reason Climatistas use the term “Ocean Acidification” is simply that it sounds so much scarier than “a very slight and probably undetectable decrease in the alkalinity of seawater”.

May 17, 2019 9:28 am

A few years ago, a commenter posted a very interesting comment/short article on his experiments with “radiative gases” over water. He found enhanced cooling. Since 3/4 of Earth’s surface is ocean, this suggested a net cooling effect of CO2.

I tried to verify that using ordinary glass oven pan–and found too much of a breeze at all times. I calculated that even a very slow zephyr of 1 mile an hour, 5280 feet, divided by 3600 seconds per hour came to over a foot a second–can’t get a practical reading outdoors. For you metric people, there is usually at least half a meter a second or more wind speed outdoors.

Your equipment, used indoors, with a window for sunshine, might be usable to find out more about this.

Patrick B
May 17, 2019 9:38 am

This is silly. It’s like two guys with a bottle of CO2 trying to show global warming.

The systems involved in real life are ridiculously complex and to bother with this type of home experiment is ridiculous.

More useful would be lots of reporting on pH around the oceans under various conditions showing what a wide variety of pH exist on an hourly basis. WUWT had an article that reported on pH fluctuations by the hour around some reefs which should have made everyone who claims the reef will be destroyed by a small fluctuation sit up and say “Oh, I didn’t know that”.

Steve Z
May 17, 2019 10:05 am

This is an interesting first-approximation experiment, but it’s not very realistic. As some commenters have noted, what about the effects of photosynthetic organisms (plankton or seaweed) which could be absorbing CO2? Also, in shallow sea water, there are many reactions between bicarbonate or carbonate ions with dissolved calcium salts, which can be taken up by mollusks and used in their shells. It would be a good idea to repeat this experiment with a sealed salt-water aquarium whose temperature could be regulated, which includes some photosynthetic organisms and mollusks and (why not?) fish.

Such an experiment would not adequately model deep-water areas (> 100 meters) of the ocean. There would still be phytoplankton in the surface layer, but any excess carbonates could be precipitated out as calcium carbonate and drop to the bottom, so that the deep oceans would be a huge sink for CO2 during cooler weather (at night, or during winter in temperate areas) when CO2 is more soluble in sea water. It would take a long time to precipitate all the calcium salts out of the oceans!

George Waldbusser
May 17, 2019 11:05 am

While a noble effort to document the sensitivity (or lack thereof) of seawater pH to CO2, the values you obtained indicate a serious flaw somewhere in your experiment. Using the well documented thermodynamic equations to calculate the rest of the carbonate system (alkalinity, total dissolved inorganic carbon, etc), and assuming your salinity was 32, temp around 13, and operating at surface pressures suggests that your total alkalinity is between 16,000 to 23,000 micromoles per KG of seawater. This is roughly 10x higher than nearly all measurements ever made of surface seawater (it is far outside the realm of even plausible). Your experiments are essentially violating some basic fundamentals of thermodynamics if your numbers are in fact correct and real.

There are two possible explanations for this, first is your 2L jar or seawater sample was contaminated by the baking soda you used in some way, or second that either (both) of the instruments you are using are incorrect. Did you calibrate either of them to ensure the values are correct? with at least a 2 point calibration to ensure appropriate responses? Also, a pH of 8.8 would be a very unusual value for seawater (but far more possible than the computed alkalinity values). What time of year and time of day was your seawater collected as this would allow others to see if perhaps local photosynthesis may be able to explain the very high pH (it would not be able to explain the alkalinity though). It is important to note that a resolution of 0.01 pH units does not mean an accuracy or precision of similar magnitude.

You can download the software for the calculations here:

And might I suggest a very good reference book on marine carbonate chemistry by Zeebe and Wolf-Gladrow called “CO2 in Seawater: Equilibrium, Kinetics, and Isotopes”.

Finally, just one correction on the statement about pH changes being less at lower pH, this is actually opposite. As more CO2 is added to seawater the change per unit added becomes greater because the solution has less ability to absorb that CO2 into the acid-base system (due to the consumption of carbonate ions via carbonic acid dissociation). The Revelle Factor is the index used to determine how sensitive the carbonate chemistry is to increases in CO2.



May 17, 2019 12:15 pm

Dr. Raveendran Narayanan USA :-
Since 1980 Oceans and Seas pH never ever came below pH 8.00.
IPCC needs $122 TRILLION for Climate Correction, BUT not C02 and GHG.

“ONE SHOT MANY BIRDS” : via @Raveendrannaray.

#youtube #climatechange #globalwarming #noozoneholes #rewritingearthscience #notco2 #2019earthsciencecommettee
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#challengingipcc #stoppingcalamites

May 17, 2019 12:15 pm

One important detail is not explained here: is the air levels of co2 kept constant during the experiment, or is it only the initial level?

Malcolm Carter
May 17, 2019 12:18 pm

Although simple, this experiment demonstrates to a general audience that even partial pressures of CO2 much larger than atmospheric levels will probably have a small effect on ocean pH. The ocean will continue to be alkaline for the foreseeable future.

Jan Kjetil Andersen
May 17, 2019 1:18 pm

Measurements from Hawaii and Bermuda show that the ph in Ocean surface water has decreased by approximately 0.04 since 1990ph readings from Hawaii and Bermuda



Jan Kjetil Andersen
Reply to  Jan Kjetil Andersen
May 17, 2019 2:09 pm

Sorry for error in link, hope this work:

Measurements from Hawaii and Bermuda show that the ph in Ocean surface water has decreased by approximately 0.04 since 1990 ph readings from Hawaii and Bermuda


Peter Foster
May 17, 2019 3:28 pm

Many Decades go I was taught in level 2 physical chemistry that glass electrode pH meters cannot measure pH if the salt concentration exceeded 0.1 mol/litre.
As sea water is higher than this could you comment on the reliability of your findings ?

Second issue: we are talking here of an equilibrium for the equation:
CO2 (aq) + 2H2O = HCO3 + H30 (Sorry cannot do the charge signs, just take them as read)

Being an equilibrium, the reaction would go in reverse and increase the CO2 if the hydronium ion concentration got too high.
At the end of the day the CO2 in the atmosphere is determined by temperature of the ocean and the state of the equilibrium between these compounds (plus carbonate) Not by the puny amount that humans add to the atmosphere
Bear in mind that bicarbonate concentration in sea water is 100 times that of CO2 (aq)

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